For a man touted as a future Manchester United boss, Mauricio Pochettinho had hardly covered himself in glory at Old Trafford.

Four Premier League visits, four defeats and not a single goal scored amounted to a dismal record at the Theatre of Dreams for the much-heralded Tottenham boss.

But all that changed last night, as Pochettino masterminded his first win at Old Trafford and increased the pressure on beleaguered United boss Jose Mourinho, who was consigned to a second straight defeat.

Amid Mourinho's current travails, Pochettinho remains a potential successor to the not so Special One, although prising him from the vice-like grip of Spurs chairman Daniel Levy would be a big ask, even for a club of United's bloated financial might.

But United continue to covet the 46-year-old, who has steered Spurs to second place and two third-place finishes in the last three years, playing an expansive, attacking style of football, at odds with the pragmatic uninspiring approach espoused by Mourinho.

Pochettino saw his side run riot at Old Trafford (Image: REUTERS)

The pressure had clearly got to Mourinho (Image: REUTERS)

Yet when Pochettino had brought Spurs to United in the Premier League in the past, they had wilted, just as they did in last season's FA Cup semi-final against Mourinho's side, succumbing 2-1, despite having taken an early lead.

Against that backdrop, last night was a huge test for Pochettino, even though all eyes were on Mourinho and whether he could secure the win he so desperately needed to halt the crisis that has engulfed him at United following the fall-out from their abject 3-2 defeat at Brighton.

Having failed to buy anyone in the close season, the first tine a Premier League club has failed to add to their squad since the introduction of the summer transfer window, Pochettinho found himself under pressure to hit the ground running.

Victories over Newcastle and Fulham saw Spurs make the perfect start, although last night's trip provided Pochettino and his squad with their first proper test of a season of huge expectation, one they ultimately passed with distinction.

Yet Spurs were forced into a policy of containment in the first-half, as United dominated and laid siege to their goal, although the home side were unable to turn their superiority into the hard currency of a goal by the break.

Lucas Moura struck twice for Spurs (Image: PA)

It took the visitors until five minutes before half-time to register their first effort on target, a tame effort from Christian Eriksen which proved no trouble to David De Gea.

Spurs got sight of the United goal again moments later, their failure to take advantage of the opening causing Pochettino to aim a frustrated kick a cluster of water bottles behind him, almost causing him to fall over in the process.

But any frustration Pochettino felt was erased five minutes after the break, when Harry Kane pulled away from Phil Jones to meet a Kieran Trippier corner and plant an unstoppable header beyond the reach of De Gea.

United were stunned, but were left reeling two minutes later when Spurs doubled their lead, Eriksen beating the offside trap and cutting the ball back for Lucas Moura to steer a clinical first-time finish low into the net.

The two-goal blitz prompted an immediate change from Mourinho, who brought on Alexis Sanchez for Ander Herrera in a desperate bid to rescue the game, but it was to little, too late, as Spurs maintained their 100 per cent start to the season and United's problems deepened.